Justices, in a 4-3 decision, said the 2013 law — which involved an issue known as “ex parte” communications between doctors and defense attorneys — could lead to the disclosure of patients' private health information that is unrelated to malpractice cases.

The law dealt with the process in which defense attorneys gather information in medical-malpractice disputes and their conversations with doctors who treat plaintiffs for reasons unrelated to the alleged malpractice. The 2013 law would allow such conversations, at least in certain circumstances, to occur outside the presence of the plaintiffs' attorneys.

Opponents of the law argued that such “ex parte” communications could lead to violations of patient privacy.

“Even the possibility that a person's extremely sensitive private medical information will be exposed is the type of governmental intrusion that the Florida Constitution protects against because it is impossible to know if an inadvertent disclosure occurred when the meetings are not only ex parte and without a judge, but also secret without a record,” Justice R. Fred Lewis wrote in Thursday's 50-page majority opinion striking down the parts of the law. “In the case of protected medical information, the danger is uniquely and unconstitutionally great because once the bell has been rung, it cannot be unrung.”

Lewis was joined in the majority by Chief Justice Jorge Labarga and justices Barbara Pariente and Peggy Quince.

But Justice Charles Canady, in a dissent joined by justices Ricky Polston and Alan Lawson, disagreed that the 2013 changes violated the constitutional right to privacy and described the majority opinion as an “unwarranted interference with the Legislature's authority.” Canady also said nothing in the law allowed disclosure of irrelevant medical information during ex parte conversations.

“In short, medical malpractice claimants waive whatever constitutional privacy rights they may have in relevant medical information,” Canady wrote. “Because the 2013 amendments do not in any way authorize the discussion of irrelevant medical information, medical malpractice claimants have no constitutional right to prevent the ex parte meetings.”

The 2013 law was part of a years-long political fight between groups such as doctors and plaintiffs' attorneys about the medical-malpractice system. Supporters of the law argued, in part, that allowing ex parte communications could lead to more information about malpractice claims and help resolve cases before they go to trial.

Thursday's ruling, which overturned a decision by the 1st District Court of Appeal, came in an Escambia County case. The plaintiff, Emma Gayle Weaver, contemplated filing a medical-malpractice lawsuit against physician Stephen Myers but was concerned about the constitutionality of the ex-parte change, according to court documents. Weaver was the wife of the late Thomas E. Weaver, whose care was at issue in the malpractice allegations.

As part of the ruling, Lewis also wrote that the majority was making clear that the privacy rights of people who have died are protected.

“Death does not retroactively abolish the constitutional protections for privacy that existed at the moment of death,” Lewis wrote. “To hold otherwise would be ironic because it would afford greater privacy rights to plaintiffs who survived alleged medical malpractice while depriving plaintiffs of the same protections where the alleged medical malpractice was egregious enough to end the lives of those plaintiffs.”

Warning of attempts to “whittle away” at a 2004 constitutional amendment, the Florida Supreme Court has rejected arguments by hospitals that they should be shielded from turning over records to plaintiffs in medical-malpractice cases.

With no explanation, the Florida Supreme Court on Tuesday rejected a request to stay the scheduled Nov. 8 execution of Patrick C. Hannon, who was sentenced to death in the 1991 murders of two men in Hillsborough County.